The present invention relates to a side airbag apparatus that protects an occupant seated in a vehicle seat from an impact by deploying and inflating an airbag on a side of the occupant when an impact is applied to a vehicle.
A side airbag apparatus having an airbag and an inflator is widely known for protecting an occupant from an impact when the impact is applied to a vehicle from a side to a vehicle seat in which the occupant is seated, for example, due to a side collision. In the side airbag apparatus, an airbag is installed in a seat back of a vehicle seat in a folded state together with an inflator. The outer shape of the airbag is formed by an airbag main body.
In the side airbag apparatus, when an impact is applied from the side on a body side portion such as a side door, which forms the side portion of a vehicle, inflation gas is supplied from the inflator into an inflation portion of the airbag, so that the airbag main body is deployed and inflated. The airbag is projected from the vehicle seat with a part of the airbag remaining in the seat back. Thereafter, the airbag main body continues being deployed and inflated forward in a narrow space between the occupant and the body side portion. The airbag main body is located between the occupant and the body side portion, which bulges inward, to restrain the occupant and reduces the impact from the side transmitted to the occupant via the body side portion.
One form of such a side airbag apparatus is disclosed in Japanese Laid-Open Patent Publication No. 2010-269646. The side airbag apparatus includes an airbag main body 161 having an inflation portion as illustrated in FIGS. 28 and 31. The airbag main body 161 is formed by sewing two main body fabric portions 162 to each other at peripheral joint portions 181, which are provided along the peripheries. The inflation portion of the airbag main body 161 is divided by a lateral partition 163 extending between the main body fabric portions 162 into an upper inflation chamber 164 located above the lateral partition 163 and a lower inflation chamber 165 located below the lateral partition 163. An inner tube 166 is provided in the inflation portion. The inner tube 166 intersects with the lateral partition 163 and extends over the upper inflation chamber 164 and the lower inflation chamber 165. An inflator 167 is located in the inner tube 166 (refer to FIGS. 29 and 31).
The airbag main body 161 of the above described side airbag apparatus is formed by a single lower ground fabric sheet 168 and a pair of upper ground fabric sheets 171. A pair of branch portions 169 is formed at the top of the lower ground fabric sheet 168. The lower part of each upper ground fabric sheet 171 is overlaid onto one of the branch portions 169. Each upper ground fabric sheet 171 is joined to the base of the corresponding branch portion 169 at an outer joint portion 172, which is arranged along the lower peripheral portion of the upper ground fabric sheet 171. Each of the halves of the lower ground fabric sheet 168 and the joined upper ground fabric sheet 171 form one of the main body fabric portions 162.
The inner tube 166 is formed by a tube ground fabric sheet 174, which has an insertion port 173 in an upper part thereof. The tube ground fabric sheet 174 has a joint portion 175 in a lower end portion (see FIG. 31), at which the tube ground fabric sheet 174 is joined to the lower ground fabric sheet 168, and a pair of joint portions 176 in an upper end portion, at which the tube ground fabric sheet 174 is joined to the branch portions 169 of the lower ground fabric sheet 168. The tube ground fabric sheet 174 also has joint portions 177 provided about the insertion port 173 (refer to FIG. 31), by which the tube ground fabric sheet 174 is joined to the lower ground fabric sheet 168 and the upper ground fabric sheets 171. Further, the tube ground fabric sheet 174 has joint portions 178, which are provided at opposite peripheral portions. The tube ground fabric sheet 174 is folded in half and the joint portions 178 are joined to form a tubular shape.
The upper peripheries of the branch portions 169 are joined to each other by inner joint portions 179. The branch portions 169, which are thus joined to each other, form the lateral partition 163. The inflator 167 is arranged in the inner tube 166 through the insertion port 173.